2017 年 12 巻 3 号 p. JFST0022
The purpose of the present work is to visualize the temperature fluctuation of water thermal plasma for biomass gasification. Another purpose is to investigate D-glucose decomposition mechanism in water thermal plasma because D-glucose is one of the main components in general biomass products. Arc temperature distributions of water thermal plasma with and without D-glucose injection were successfully visualized by high-speed camera. Two synchronized arc images in different wavelengths of Hα and Hβ were observed owing to appropriate optical band-pass filters with negligible other emissions from the arc. The arc temperature was measured based on Boltzmann-plot method. Measured arc temperature without D-glucose was 9000 K, and that with D-glucose was 7500 K. These temperatures were sufficiently high to decompose D-glucose completely. Furthermore, frequency analysis of arc fluctuation revealed that the time period of arc fluctuation was sufficiently shorter than that of the time constant of D-glucose decomposition. These results implied that the influence of arc fluctuation on D-glucose decomposition was negligible. In addition, the decomposition mechanism of D-glucose was discussed on the basis of the analyses of the products in vapor, liquid, and solid phases. They were converted from D-glucose through the water thermal plasma. Decomposition rate of D-glucose reached 99%. Gaseous product contains more than 86% of syngas, H2 and CO. This ratio is much higher than that in conventional gasification device. From these characteristics, water plasma system is suitable device for biomass utilization.